DE19631520C2 - Process and plant for the sol-technical extraction of evaporites and preparation of salt solutions - Google Patents

Abstract

The invention relates to a method and a plant for the sol-technical extraction of evaporites and preparation of the saline solution obtained, in particular for the dissolution of salts, evaporation and cooling of the saline solution obtained and crystallization of salts under subtropical climatic conditions. DOLLAR A The object of the present invention is to develop a method and a plant for the sol-technical extraction of evaporites and preparation of salt solutions using the dependence of the solubility on the temperature for various salts, which under subtropical and tropical climatic conditions while avoiding the from the high air humidity and the considerable rainfall resulting disadvantages can be used. DOLLAR A According to the invention the object is solved by claims 1 and 9. Advantageous embodiments of the invention are contained in the associated subclaims 2 to 8 and 10 to 12.

Description

The invention relates to a method and a plant for the extraction of solar technology Evaporites and preparation of the saline solution obtained, in particular to dissolve Salting, evaporation and cooling of the saline solution obtained and crystallization of Salting in subtropical and tropical climatic conditions. The invention can can also be used to process naturally occurring salt solutions.

To evaporate water from saline solutions, an amount of energy must be used corresponds to the heat of vaporization of water from the respective salt solution. For For this purpose, two technologies are known from the prior art. On the one hand, the salt solution is heated to boiling, using a Vacuum the boiling temperature can be reduced. This type of water evaporation is carried out in specially designed evaporation plants. By using Waste heat and secondary energy utilization will reduce the primary energy use acceptable level lowered.

The use of evaporation plants is suitable, in addition to the concentration of the Saline solution also to collect and use the water as condensate.

Solar evaporation is only used to concentrate salt solutions. This is done in large evaporation basins with the help of solar radiation and a very low humidity at ambient temperature and atmospheric pressure from the introduced saline water evaporated. The evaporated water is transferred to the Ambient air emitted and is in contrast to the above. Technology no longer one Recycling accessible.  

It is obvious that the solar evaporation only under special climatic conditions Conditions possible or economically sensible. But meet favorable climatic Conditions such as B. at the Dead Sea, then the solar evaporation of Salt solutions economically superior to water evaporation in evaporation plants. Now, in many subtropical and tropical areas of the world, the level is similar You can find the intensity of the sunshine like at the Dead Sea, but at the same time it is Air humidity too high for effective water evaporation or Precipitation amounts largely compensate for the evaporation amounts achieved Water. The use of seasonal dry periods is also necessary Dimensions of the evaporation basin so large that an economical solar evaporation is impossible.

As a result, in these cases, evacuation systems are used, even if this, due to the high outside temperatures, is often not so energetically work cheaply, such as in temperate climates.

Application examples that the state of the art described above in large Demonstrating the breadth of variation, there is in the areas of NaCl evaporated salt production, potash fertilizer production and desalination.

Furthermore, US Pat. No. 4,211,613 describes a method for using geothermal energy, especially known for the production of steam, with a downstream Evaporation of the mineralized water causes salt to crystallize. The well-known fact of the state of the art that Evaporation of water also when cooling heated cooling water in cooling towers he follows. Of course, this water evaporation effect also occurs much less frequently practiced cooling of salt solutions in cooling towers (DD 139 354 and DD 155 316).

It is also generally known that solar cells for heating domestic water increasingly applied. The state of the art in this field includes that for the principle of the solar cell on a so-called solar pond is transmitted, d. H. a basin filled with liquids of different densities changes the incident solar radiation into heat energy. As typical examples, the state describe the technology for the solar pond,  are DE 34 22 481, G 85 27 665.0, and the publication "Salt Ponds: Energy Phenomenom "(Compressed Air Magazine, Jan. 1986).

The dissolution of salt deposits by means of isolation is generally known. Widespread is the NaCl solution with water as a solvent. The state of the art for selective Isolation of potash deposits using a heated solvent describes the Documents DD 206 179, DD 208 389, DD 271 731, DD 271 732, DD 277 718, DD 291 601 and the publication of Colome and Rose's "Operation of a potassium ore pilot cavern. ", SMRI meeting, October 1994, Hanover and von Neuber, L. "Potash Salt Extraction by Guided Wrapping Out" in Bergakademie, 17th Volume, Issue 11, November 1965, pp. 664 to 670.

The present invention has for its object a method and a system for Sol technology extraction of evaporites and preparation of salt solutions under Exploitation of the dependence of the solubility on the temperature with different salts to develop which under subtropical and tropical climatic conditions Avoidance resulting from the high humidity and the significant Disadvantages resulting in precipitation amounts can be used.

According to the invention the object is solved by claims 1 and 9. Beneficial Developments of the invention are in the associated subclaims 2 to 8 and 10 to 12 included.

According to the process according to the invention for the extraction of evaporites by brine and preparation of salt solutions becomes dependent on the respective process phase Solvent to be selected in a solar pond using solar energy Ambient temperature warmed to approx. 60 ° C-80 ° C.

The heated solvent is fed to a cavern to be removed, the Cavern temperature increased compared to the deposit temperature. Then there is one Isolation of the cavern. The resulting heated production brine becomes one Cooling system supplied and there at ambient temperature with water evaporation cooled, with crystallization due to cooling and water evaporation of solid and then a separation of solid and cold mother solution he follows.

This can be used particularly advantageously in the sol-technical extraction of salts become. In this case, the solvent for the sol technical  Extraction first heated in a solar pond and then fed to the cavern and the from the cavern, more concentrated salt solution of evaporation and Cooling fed.

According to an outstanding feature of the invention, the cooling system supplied solutions in a number of cycles resulting from the temperature difference between solution and environment divided by the realizable cooling span per Pass through a cooling system, cooled to ambient temperature, the necessary number of cycles for cooling by several parallel operated Cooling systems and / or by repeatedly circulating the solutions in at least one Cooling system can be realized.

Especially when extracting salts, the solubility of which strongly depends on the temperature depends, the previous heating of the solvent makes sense, as disproportionate enrichment of the valuable component in the from the cavern promoted saline solution and thus in a subsequent evaporation and Cooling a disproportionate crystallization of the valuable component is achieved.

The evaporation and cooling process is particularly advantageous by the Incorporation of the dissolution process intensified, since higher from a saline solution Concentration achieved by dissolving a deposit at a higher temperature in which the evaporation of the cooling accompanied by water more salt crystallized.

Because of the physical laws of thermal energy demand at Evaporation is about 10 times higher than when heating an equal amount of water or solution, can be achieved by leading the dissolution process to generate the evaporated saline solution at a higher temperature level Total heat energy requirements can be reduced.  

The integration of a solar fund according to the invention enables unhindered use solar energy, without the function being affected by precipitation, if the necessary liquids of different density from process-specific Salt solutions are synthesized, the salt solution to be heated being the lowest Represents the layer with the highest density and the top layer with the lowest Dense water is. The layer thickness of the water can therefore be made variable.

Another advantage of the combination of solar pond and cooling system according to the invention is the large heat storage capacity of the solar pond, even with little or no Sunshine - especially at night - allows continuous operation, although still from which can then benefit from the lower ambient temperature. According to the invention to increase the heat storage capacity, the layer thickness of the solution to be evaporated varies in the solar pond.

There is also no significant negative influence from precipitation arrangement according to the invention of the device integrated within the cooling system, which should be suitable, the supersaturation of a emerging from a cooling device Dismantling the solution and at the same time thickening the crystals that form, to be expected since the concentrated brine or a suspension of concentrated brine and Crystallized salts offer small surfaces or heavy rainfall can be effectively withdrawn at short notice.

According to a special feature of the invention, water is used as the solvent, whereby a non-selective isolation of a cavern can be carried out. In particular, this form of isolation is used to prepare the caverns for production applied. A production brine is obtained which, in terms of its composition, is the Relations of the minerals in the deposit are reflected. The in this variant after cooling and separation, the cold mother solution obtained becomes another Feature of the invention  circulated through return to the Solar Pond. The solution can also be complete or partially as a repulsion solution to the circuit of a separate, separate selective isolation phase are available plant. It may look like this a further feature of the invention for feeding the solution into the solar pond and / or a supply line to the heated production brine for selective isolation. How the cold mother liquor is administered depends on the composition or Concentration of the solution.

According to a particularly preferred feature of the invention, the selective phase takes place Isolation of the cavern depending on the composition of the solvent, the composition of the solvent depending on the Deposit composition, deposit temperature and the applicable Equilibrium system of solubility is chosen. This can be particularly advantageous Influence on the composition of the resulting production brine. To close the process cycle, the cooling process is followed by separation cold mother solution depending on the concentration of the process solution in the solar Pond and / or as a repulsion solution to the circuit of a further separate separate Given plant.

According to another feature of the invention can be aimed at evaporation maximum concentration from the rejection solution through solar heating in the Solar Pond Evaporation brine are generated, the heated evaporation brine a cooling system is fed and cooled there at ambient temperature with water evaporation is, due to the cooling a crystallization of solid and a Separation of solid and cold mother solution takes place and the cold mother solution through Mix with the rejection solution and return to the Solar Pond as long as in the circuit is carried out until a concentration suitable for further use and Reduction of the solution is achieved. The concentration of the solution thus achieved is suitable for landfill in isolated caverns or external landfill cavities or for  Sale. According to a further feature of the invention, the caverns displaced solution as a result of the underlaying in the cavern by landfill brine too be added to a production brine of a process according to claim 1 or 5.

The above description of the process already leaves the essential components of the recognize the associated system. Otherwise, in this regard, the following Referred to the description of the figures, which also contains general features. The invention will be explained in more detail by the following exemplary embodiments.

In the drawing they show

Fig. 1 shows a process scheme for selective solution mining a cavity,

Fig. 2 shows a process scheme of using water as the solvent for non-selective solution mining,

FIG. 3 shows a process diagram for a process by which a Eindampflösung generated in the solar pond is processed further.

The method according to the invention makes it possible to use solar energy Solvents for the recovery of evaporites from a deposit heat, so that a higher solubility in the recoverable component to realize and the highly saturated solution obtained from the caverns effectively To cool ambient temperature, by cooling and evaporation conditionally, the valuable component crystallized out.

Depending on the composition of the deposit, the respective equilibrium systems of solubility must be used as the physical-chemical basis. Typical examples are:

• - binary system NaCl-H ₂ O
• - KCl-NaCl-H ₂ O ternary system
• - NaHCO ₃ -Na ₂ CO ₃ -H ₂ O ternary system
• - Quaternary system MgCl ₂ -KCl-NaCl-H ₂ O
• - Quaternary system NaHCO ₃ -Na ₂ CO ₃ -NaCl-H ₂ O
• - Quinary system MgSO ₄ -MgCl ₂ -KCl-NaCl-H ₂ O
• - Quinary system CaCl ₂ -MgCl ₂ -KCl-NaCl-H ₂ O
• - Hex system CaSO ₄ -MgSO ₄ -MgCl ₂ -KCl-NaCl-H ₂ O

When using the sol-technical extraction of evaporites and the preparation of the saline solution to marketable products are different Concentration levels in the process solutions according to the respective process phases to be found.

Usually these are:

• - Process solutions from the production phase of the caverns and the brine preparation  
• - Low concentration process solutions from the preparation phase of the Development of the caverns and the non-selective isolation of the deposit or Rinsing solutions from brine processing and
• - highly concentrated process solutions from the production phase for sales or Landfill.

The following individual examples explain the process according to the invention for the typical process phases mentioned above. It should be noted that due to the large number of possible variations that result from

• - a different deposit composition,
• - a different deposit temperature and
• - the applicable equilibrium system of solubility

result, the exemplary embodiments each only a special application describe.

I.

When extracting carnallite (MgCl ₂ × KCl × 6H ₂ O) with the aim of producing KCl from an exemplary deposit, along with carnallite (approx. 30-80%), halite (NaCl) is an essential accompanying mineral.

Furthermore, the accompanying minerals Sylvin (KCl) and tachydrite (CaCl ₂ × 2MgCl ₂ × 6H ₂ O) have to be considered.

This deposit composition determines in general and in particular with the Obtaining by isolation the composition of all process solutions and thus also in which equilibrium system of solubility the heating, dissolving, cooling, Evaporation and crystallization processes take place.

In the present case, the CaCl ₂ -MgCl ₂ -KCl-NaCl-H ₂ O system applies.

The basic principle of the extraction of KCl from the carnallite with simultaneous Gaining the accompanying Sylvin is the targeted exploitation of the dependency of the KCl's solubility from temperature in a cycle of heating and Dissolution as well as cooling and crystallization.

The method according to the invention is explained in more detail with reference to FIG. 1.

In carnallite caverns prepared for production, with a volume flow of 40-80 m ³ / h per cavern, a carnallite-specific solvent 1 unsaturated in KCl with the following composition

Solvent 1

• CaCl ₂ : 13 g / 1000 g H ₂ O
• MgCl ₂ : 300 g / 1000 g H ₂ O
• - KCl: 76 g / 1000 g H ₂ O
• - NaCl 56 g / 1000 g H ₂ O
• - Density: 1.240 g / cm ³

pumped in.

By pumping the heated solvent at 60-80 ° C the Cavern temperature compared to the deposit temperature (approx. 28 ° C) approx. 50-60 ° C increased.

As a result of the temperature increase, the carnallite is dissolved in cavern 2 , which is selective due to the choice of the particular solvent composition, ie halite dissolves only to a very limited extent.

A production brine 3 of the following composition is obtained from the cavern:

Production brine 3

• - CaCl ₂ : 15 g / 1000 g H ₂ O
• MgCl ₂ : 306 g / 1000 g H ₂ O
• - KCl: 85 g / 1000 g H ₂ O
• - NaCl 60 g 11000 g H ₂ O
• - Density: approx.1.258 g / cm ³
• - Temperature: approx. 55 ° C

The accompanying minerals Sylvin and Tachydrite are due to their good solubility dissolved.

The production brine 3 obtained from the cavern 2 is now fed to a cooling system, which together form the cooling system of a cooling tower 4, and there is a crystallizer / thickener. 5 In this refrigeration system, the production Sole 3 is preferably result in a number of cycles divided from the temperature difference between the production brine and the surrounding area by the realizable Abkühlspanne per pass through a cooling tower, cooled to ambient temperature. The necessary number of cycles during cooling can be realized by several cooling tower / crystallizer / thickener units operated in parallel or by a unit with multiple circulation of the solution quantities via the cooling tower and the crystallizer / thickener.

Based on the basic technical principle of cooling in cooling tower 4 , water evaporation takes place at the same time.

Due to the cooling and simultaneous evaporation of water, crystallization of solid takes place in the crystallizer / thickener 5 in accordance with the solubility equilibrium in the system CaCl ₂ -MgCl ₂ -KCl-NaCl-H ₂ O.

The crystallizer / thickener 5 is used to separate crystallized solid 6 and cold carnallite mother liquor 7 .

The composition is as follows:

Crystallized solid 6

• - KCl: 1.5 t per 100 m ^{3 of} production brine
• - NaCl 1 , 3 t per 100 m ^{3 of} production brine
• - Temperature: approx. 35-40 ° C

Mother solution 7

• CaCl ₂ : 16 g / 1000 g H ₂ O
• MgCl ₂ : 317 g / 1000 g H ₂ O
• - KCl: 71 g / 1000 g H ₂ O
• - NaCl 48 g / 1000 g H ₂ O
• - Density: approx.1.265 g / cm ³
• - Temperature: approx. 35-40 ° C

The crystallized solid is a KCl / NaCl mixture, which is temporarily stored and in subsequent process stages is processed into marketable products.

To close the required process cycle, after cooling and separation of the KCl's carnallite mother solution 7 is applied to a solar pond. 8 In the solar pond, the carnallite mother solution is heated to 60-80 ° C by means of solar energy, whereby there is an under-saturation of KCl.

The heated carnallite mother liquor can thus be fed back to the caverns for dissolving the carnallite as solvent 1 .

Due to the fact that the process is run in a cycle, the process solutions are concentrated in MgCl ₂ . This is only in certain process phases, e.g. B. after rinsing breaks, desirable. There is therefore a need to remove the amount of MgCl _{2 introduced} into the process during the dissolution of carnallite from the process. This is solved by the rejection ( 9 ) of cold carnallite mother solution. Depending on the evaporation achieved during the cooling of the production brine 3 in the cooling tower 4 , there is the possibility in the described cycle process of solutions with lower MgCl ₂ , which are often more concentrated in KCl, for example rejection solution 10 from a process cycle, as in exemplary embodiment 2 set out to feed. Depending on the KCl content, these should be fed to the process at two different points. In the case of higher KCl contents, solutions with lower MgCl _{2 will be} fed into the production brine 3 . In the case of low KCl contents, solutions with lower MgCl _{2 are introduced} into the carnallite mother solution 7 upstream of the solar pond. The decision about higher or lower KCl contents is to be made with the help of a balance sheet calculation of the mixing process of the solutions with lower MgCl ₂ with the carnallite mother solution.

Is according to the accounting KCl crystallized, the case, "higher KCl content" is given and the addition is made to the production brine 3, however, is not expected KCl-crystallization at the mixing of the solutions with lower MgCl ₂ with the carnallite mother solution, the Case "low KCl content" given and added to the carnallite mother solution 7th

In the case of a repulsion solution 10 with the following composition, the case is "higher KCl content".

Repulsion solution 10

• - CaCl ₂ : 3 g / 1000 g H ₂ O
• MgCl ₂ : 168 g / 1000 g H ₂ O
• - KCl: 121 g / 1000 g H ₂ O
• - NaCl 137 g / 1000 g H ₂ O
• - Density: approx.1.235 g / cm ³
• - Temperature: approx. 35-40 ° C

Based on a water balance of the process, 25 m ^{3 of} this repulsion solution 10 per 100 m ^{3 of} production brine can be added to production brine 3 before it is fed into the cooling system. This changes the amounts of crystallized solid 6 and carnallite mother solution 7 given above as follows:

Crystallized solid 6

• - KCl: 2.7 t per 100 m ^{3 of} production brine
• - NaCl 2 , 9 t per 100 m ³ production brine
• - Temperature: approx. 35-40 ° C

Carnallite mother solution 7

• - CaCl ₂ : 15 g / 1000 g H ₂ O
• MgCl ₂ : 300 g / 1000 g H ₂ O
• - KCl: 76 g / 1000 g H ₂ O
• - NaCl 56 g / 1000 g H ₂ O
• - Density: approx.1.261 g / cm ³
• - Temperature: approx. 35-40 ° C

The cycle process is now not only closed technically, but also with regard to the MgCl ₂ and water balance.

Generally speaking, this means that in example 1 the heating, saturation, cooling, evaporation and crystallization cycle is realized with the primary aim of saturation, evaporation and cooling at a constant MgCl ₂ concentration level.

II.

Embodiment 2 is intended to be a further variant of the application of the inventions method according to the invention also using the example of that already in exemplary embodiment 1 Explain the stated carnallite deposit.

Therefore, the theoretical basics, as in Example 1 at the beginning described, also for the embodiment 2.

The embodiment 2 is explained in more detail with reference to FIG. 2.

In general, initial cavities are excavated to prepare the caverns for production. This is done using water with a volume flow of 5-25 m ³ / h per cavern.

Before the water 11 is pumped into the cavern, it is fed to a solar pond 18 . In the Solar Pond, water 11 is heated to 60-80 ° C using solar energy.

By pumping in the heated water at 60-80 ° C Cavern temperature compared to the deposit temperature (approx. 28 ° C) approx. 50-60 ° C increased.

In the cavern 12 there is a dissolution of the carnallite, which is non-selective due to the choice of the solvent water, ie the skin also largely dissolves. A production brine 13 , which reflects the relations of the minerals in the deposit with regard to the composition, is obtained. The following average composition of the production brine 13 can be assumed to be typical, taking into account the alternative shown below:

Production brine 13

• - CaCl ₂ : 3 g / 1000 g H ₂ O
• MgCl ₂ : 127 g / 1000 g H ₂ O
• - KCl: 90 g / 1000 g H ₂ O
• - NaCl 140 g / 1000 g H ₂ O
• - Density: approx.1.19 g / cm ³
• - Temperature: approx. 55 ° C

The accompanying minerals Sylvin and tachydrite were due to their good solubility dissolved.

The production brine 13 obtained from the cavern 12 is now fed to a cooling system which consists of a cooling tower 14 and a crystallizer / thickener 15 . In this refrigeration system, the production brine is 13 resulting in at least a number of cycles divided from the temperature difference between the production brine and the surrounding area by the realizable Abkühlspanne per pass through a cooling tower, cooled to ambient temperature and, based on the basic technical principle of the cooling in the cooling tower 14 , evaporated at the same time. As a result of the cooling and evaporation, a maximum KCl concentration in the solution, which is defined by the appropriate equilibrium system of solubility, should preferably be achieved.

The necessary number of cycles can be cooled in parallel by several operated cooling tower / crystallizer / thickener units or by a unit with multiple circulation of the solution quantities over the cooling tower and Crystallizer / thickener can be realized.

Due to the cooling and simultaneous evaporation of water, crystallization of solid takes place in the crystallizer / thickener 15 in accordance with the solubility equilibrium in the system CaCl ₂ -MgCl ₂ -KCl-NaCl-H ₂ O.

The crystallizer / thickener 15 separates the crystallized solid 16 and cold carnallite mother liquor 17 .

The composition is as follows:

Crystallized solid 16

• - KCl: 0 t per 100 m ^{3 of} production brine
• - NaCl 3, 3 t per 100 m ³ production Sole
• - temperature approx. 35-40 ° C

Carnallite mother liquor 17

• - CaCl ₂ : 3 g / 1000 g H ₂ O
• MgCl ₂ : 168 g / 1000 g H ₂ O
• - KCl: 121 g / 1000 g H ₂ O
• - NaCl 137 g / 1000 g H ₂ O
• - Density: approx.1.235 g / cm ³
• - Temperature: approx. 35-40 ° C

The crystallized solid in this case is NaCl, which is temporarily stored and in subsequent process stages is processed into marketable products. Basically However, within the scope of the technical design of the process, a KCl / NaCl Crystallize mixture.

If, in certain production phases, significantly lower concentrations of the production brine 13 occur compared to the above-mentioned composition, alternatively, by returning part or all of the cooled carnallite mother solution 17 into the process circuit, a concentration can be reached until a maximum KCl concentration in the solution is reached defined by the applicable solubility system. The cooled carnallite mother solution 17 is returned to the volume flow of the water 11 upstream of the solar pond or in a separate solar pond / cavern system.

By managing the process in a cycle, the process solutions are concentrated. To balance the process, cold carnallite mother liquor is carried out as rejection solution 10 from the process.

Generally speaking, this means that in example 2 the heating, saturation, cooling, evaporation and crystallization cycle is realized with the primary aim of saturation and evaporation at a sliding input concentration level of MgCl ₂ .

III.

The embodiment 3 explains a further variant of the application of the The method according to the invention is also based on the example of the one already in exemplary embodiment 1 indicated carnallite deposit.

Therefore, the theoretical basics, as in Example 1 at the beginning described, also for the embodiment 3.  

The embodiment 3 is explained in more detail with reference to FIG. 3.

To balance the overall process with respect to MgCl _{2, there} is a need to run MgCl ₂ from the process, as already explained in exemplary embodiment 1. Since the rejection solution 9 coming from a process analogous to embodiment 1 is normally still too low for the landfill, the heating, saturation, cooling, evaporation and crystallization cycle is carried out with the primary aim of evaporation to the maximum MgCl ₂ concentration.

For this purpose, carnallite mother solution 24 is mixed with rejection solution 9 and fed to a solar pond 19 . In the Solar Pond, the solution mixture is heated to 60-80 ° C by means of solar energy and thus the evaporation solution 20 is generated.

The evaporation solution 20 is now fed to a cooling system which consists of a cooling tower 21 and a crystallizer / thickener 22 . In this cooling system, the evaporation solution 20 is cooled to ambient temperature at least in a number of cycles, which result from the temperature difference between the evaporation solution and the environment divided by the achievable cooling span per run through a cooling tower, and simultaneously based on the basic technical principle of cooling in the cooling tower 21 evaporated.

The necessary number of cycles can be cooled in parallel by several operated cooling tower / crystallizer / thickener units or by a unit with multiple circulation of the solution quantities over the cooling tower and Crystallizer / thickener can be realized.

Due to the cooling and simultaneous evaporation of water, the crystallization of carnallite takes place in the crystallizer / thickener 22 in accordance with the solubility equilibrium in the system CaCl ₂ -MgCl ₂ -KCl-NaCl-H ₂ O.

In the crystallizer / thickener 22 , the crystallized solid 23 and cold carnallite mother solution 24 are separated .

After performing approximately 10 evaporation cycles (heating, evaporation, cooling, Crystallization and solid / liquid separation is the following amount  crystallized solid and the composition of the carnallite mother liquor is as follows:

Crystallized solid 23

• - Carnallite: 24.5 t per 100 m ³ rejection solution ( 9 )
• - NaCl 4, 5 t per 100 m ³ kick solution (9)
• - Temperature: approx. 35-40 ° C

Carnallite mother liquor 24

• - CaCl ₂ : 32 g / 1000 g H ₂ O
• MgCl ₂ : 560 g / 1000 g H ₂ O
• - KCl: 3 g / 1000 g H ₂ O
• - NaCl 4 g / 1000 g H ₂ O
• - Density: approx.1.355 g / cm ³
• - Temperature: approx. 3540 ° C

The crystallized solid in this case is a carnallite / NaCl mixture, which is cached and in subsequent process stages to marketable products is processed.

The management of the process in closed-loop operation leads to a desired reduction of the process solutions to approx. 50% in addition to the concentration. The above concentration is suitable for landfill of the carnallite mother solution 24 in isolated carnallite caverns or in external landfill cavities. It is also possible to sell 25 of these highly concentrated brine.

In the internal dump in ausgesolte Carnallitkavernen a solution falls as a result of the stratification and displacement in the cavity, corresponding to the production Sole 3 in the embodiment 1, and can additionally be fed there.

Claims (12)

1. A method for the soltechnical extraction of evaporites and preparation of salt solutions, for use under subtropical and tropical climatic conditions, characterized in that
a solvent to be selected depending on the respective process phase is heated in a solar pond to about 60 ° C - 80 ° C by means of solar energy above ambient temperature,

• the heated solvent is fed to a cavern to be isolated, the cavern temperature increasing compared to the deposit temperature and the cavern being isolated,
• - The heated production brine is fed to a cooling system and is cooled there at ambient temperature with water evaporation, with the crystallization of solid and then a separation of solid and cold mother solution due to the cooling.

2. The method according to claim 1, characterized in that Water is used as a solvent and a non-selective isolation of the Cavern is done. 3. The method according to claims 1 or 2, characterized in that the cold mother solution resulting from cooling and separation Return to the Solar Pond in a circuit and / or as a rejection solution the cycle of a separate separate in a selective isolation phase located system is supplied.   4. Process according to claims 1 to 3, characterized in that the cold mother solution resulting from cooling and separation as a rejection solution the solar pond and / or the heated production brine of a connected, separate system in selective isolation phase is fed. 5. The method according to claim 1, characterized in that the phase of selective isolation of the cavern depending on the Composition of the solvent takes place, the composition of the Solvents depending on the composition of the deposit, Deposit temperature and the applicable equilibrium system of solubility is chosen. 6. The method according to claim 5, characterized in that the cold mother solution resulting from cooling and separation Return to the Solar Pond in a circuit and / or as a rejection solution the circuit of a further separate, separate system is fed. 7. The method according to claims 5 or 6, characterized in that

• the rejection solution is heated in a solar pond to about 60 ° C.-80 ° C. by means of solar energy above ambient temperature, an evaporation brine being formed,
• the heated evaporation brine is fed to a cooling system and is cooled there at ambient temperature with evaporation of water, with the crystallization of solid and a separation of solid and cold mother solution due to the cooling,
• - The cold mother solution is mixed with the rejection solution and returned to the Solar Pond until a suitable concentration and reduction of the solution is achieved.

8. The method according to claims 5 to 7, characterized in that the solution in already isolated caverns and / or external landfill cavities is deposited, the solution of the production brine being displaced from the caverns a process according to claim 1 or 5 is added. 9. Plant for the soltechnical extraction of evaporites and preparation of the obtained saline solution for use among tropical and subtropical Climatic conditions, consisting of at least one solar pond and at least one a cooling system, the cooling system comprising a cooling tower connected to a  Technically, crystallizer or thickener is linked, which is suitable for supersaturation to dismantle a solution emerging from the cooling tower and at the same time the thicken the resulting crystals. 10. Plant according to claim 9, characterized in that the Solar Pond process solutions of different densities with variable layer thickness comprises, the uppermost layer with the lowest density being water. 11. Plant according to one of claims 9 to 10, characterized in that Solar Pond and / or cooling tower and / or arranged below the cooling tower Crystallizer or thickener with appropriate supply or connection lines at least one salt deposit and / or at least one landfill cavity are connected. 12. Plant according to one of claims 9 to 11, characterized in that individual facilities belonging to the system with several connected systems are connected to each other.